Method and device for the recording of body movements

ABSTRACT

The invention relates to a method for recording the position, location or movement of a body part of a patient and a device for recording the position, location or movement of a body part or a medical instrument. According to the invention, a graphic marker is connected with the body part or the instrument and an image of the body comprising the graphic marker is generated by an image recording camera. The image is processed by a processor device as an image file. The invention is characterized in that at least one geometric size characteristic of the graphic marker is known, wherein the processor device determines the position, location and/or movement of the graphic marker in the three-dimensional space and in quantitative manner relative to the image recording camera by means of the known size characteristic. The invention offers, without the need of manual calibration of the measuring system, a substantial automatization and a high measuring precision during the determination of position and movement in the three-dimensional space. Simultaneously, the expenditure on equipment can be reduced and the reaction to the object or body part to be measured or to the patient can be minimized.

RELATED APPLICATIONS

This application is a 35 U.S.C. 371 national stage filing fromInternational Application No. PCT/DE2007/00146 filed Jan. 23, 2007,which claims priority to German Application 10 2006 004 197.6 filed Jan.27, 2006 and German Application No. 10 2006 003 945.9 filed Jan. 26,2006, the teachings of all which are incorporated herein by reference.

The invention relates to a method for recording of position, location ormovement of a body part of a patient by means of electronic imagerecognition and a device for recording of position, location or movementof a body part of a patient or a medical instrument.

Methods for recording of the position, the spatial location, or ofmovement paths, at least of parts of the human body, or in general ofbody parts of patients or corresponding devices, respectively, areemployed in a variety of different fields, based, for example, onscience and research, from the medical field to media production.

It is, for example, known to record position, location or movement ofbody limbs by means of mechanical or electromechanical detectors, and totransfer the obtained data preferably to electronic processor andstorage media. This way it is possible to generate, for example,movement evaluations within the scope of the training supervision ofathletes; it is possible, based on the obtained position and movementdata, to control mechanical actuators such as robot arms or to generatedigital visualizations in the film and media field; or the obtained dataare used, for example, for support at the medical diagnosis or therapy.

Besides the mechanical or electromechanical detectors for determinationof position, location or movement of body limbs or body parts,furthermore contactless detector systems operating, for example,optically or with ultrasound and the like, are known. In case of suchknown contactless detector systems, the body parts to be evaluated aregenerally first provided with easily traceable reflectors orilluminating points, such as, for example, glued on light-emittingdiodes or the like. Subsequently the movement sequence to be studied isrecorded by pointing a sensor unit or an image recording camera,respectively, towards the body parts provided with the illuminatingpoints, and then generating corresponding film or image records,respectively, of the body parts or illuminating points, respectively.

Moreover, in the medical field, devices are known for detection of theposition and for navigation, respectively, of medical instruments, forexample surgical instruments, the position or the movement path of whichis traced in a similar manner at least by portions of the medicalinstrument. Hereby the surgeon is enabled, for example by means of amanually controlled manipulator, to a more precise working than by handbecause by the manipulator, the medical instrument can be directed moreprecisely due to the position tracing and due to a movementtransmission, and inaccuracies or shaking of the surgeon can becompensated hereby. In addition, such devices for detection of theposition or for navigation, respectively, of medical instruments areused in so-called robot medicine, for example for the automaticallycontrolled milling of the femoral neck for the purpose of the subsequentanchoring of a hip joint endoprosthesis.

Such known methods and devices, respectively, for recording of position,location or movement of body parts of patients and devices,respectively, for movement tracing of medical instruments are, however,on the one hand in most cases complicated, and moreover, allow at best amedium accuracy with respect to the determination of the position or thespatial location, respectively, when recording. For increasing theaccuracy, in case of the known methods or devices, respectively, it isuniformly necessary to calibrate the relative position between thetraced body part or instrument and the tracing sensor system in acomplicated manner, in order to thereby be able to make the desiredexact quantitative statements about the location or the movement curves,respectively, of the traced body parts or instruments, whereinadditionally with each major change between the traced body part orinstrument and the tracing sensor system, a new calibration is necessaryto eliminate measurement errors.

With this background it is the object of the present invention toprovide a method for recording of position, location or movements ofbody parts and a device for position and movement tracing, respectively,of body parts or medical instruments, whereby the mentioned existingdrawbacks of the prior art are resolved. More preferably, hereby a highdegree of automatization as well as a very high accuracy of positiondetermination is to be achieved; the method and the device are furtherto be used with a particularly low equipment expenditure having aparticularly high flexibility at the same time, and the reaction on theobject or body part and on the patient, respectively, through therecording and measurement, respectively, is to be minimized.

The method according to the invention serves for recording of position,location or movement of at least one part of a body of a patient. Forthe purpose of simplicity and unity the term “patient” is usedconsistently, wherein hereby, however, no limitation of the invention tomedical fields is implied. Moreover, the term “patient” in the contextof the present invention is to be understood as in the broadest sense asa synonym for “living creature to be observed”.

Here the at least one part of the body of the patient first is arrangedin an object space and can be imaged by means of at least one imagerecording camera into an image space. The differentiation in “objectspace” and “image space” is made here to be able to make a clearconceptual differentiation between the geometrical relationships at theobject or the patient, respectively, on the one hand (object space), andthe geometrical relationships within the image (image space) generatedby the image recording camera.

Within the scope of the method according to the invention, here in afirst process step a) at least one graphic marker is connected with atleast one body part of the patient. In this case, at least onegeometrical size characteristic of the graphic marker is known. Only asan illustrative, but by no means limiting example for such a graphicmarker to be connected with the body part of the patient, a circularglued marker is mentioned as the simplest case, wherein in case of thesimple circular marker the size characteristic consists in the knowndiameter of the circular marker in the object space.

In a further process step b), an image of at least the area of the bodypart comprising the graphic marker is then generated by the imagerecording camera.

Then, in a further process step c), a transfer of the image as an imagefile, for example a pixel image, from the image recording camera into anelectronic storage or processor device, respectively, is carried out.

In a further process step d), within the image space of the image file,an automatic localization of the image of the graphic marker containedin the image file is then carried out by means of an application of animage recognition procedure by the processor device to the image file.

During a further process step e), then the size characteristic of thegraphic marker in the image space is determined. This means, in theabove mentioned example of the simple circular marker used as thegraphic marker, that by the processor device in this process step, forexample, it is determined to how many image pixels strung together (ifthe image file exists in the form of a pixel image) the diameter of theimage of the circular marker in the image file is equal to.

In a further process step f), then the position and/or the location ofthe graphic marker in the object space relative to the image recordingcamera is determined. This takes place on the basis of the sizecharacteristic of the graphic marker now known in the object space aswell as in the image space. In other words, in this process step, anautomatic calibration of the image recording camera takes place withrespect to each of the present geometrical relationships between thelocation of the image recording camera and the location of the body partor the location of the graphic marker arranged thereon, respectively.

Through the size characteristic known in the object space as well as inthe image space (example: the circular marker has the known diameter “20mm” in the object space and at the same time the determined diameter“328 pixel” in the image space), in consideration of the imagingproperties of the camera lens, the actual distance between the graphicmarker and the image recording camera, as well as the distance betweenthe graphic marker and the optical axis of the image recording cameracan be determined. In addition, a potential angle-tilting of the graphicmarker relative to the optical axis of the image recording camera can bedetermined. In the example of the simple circular marker, this can takeplace on the basis of the readily possible detection of the twohalf-axes of the generally elliptical image of the circular marker inthe image space.

The method according to the invention thereby allows the determinationof the position in three-dimensional space as well as the detection ofthe angular position of the body part or the graphic marker connectedwith the body part, respectively, relative to the image recordingcamera, without the necessity of a manual calibration of the camera.Thereby, basically a plurality of possible applications is alreadydeveloped, respectively considerably simplified and improved compared tothe methods known from the prior art. Hence, with the method accordingto the invention, a body part of a patient provided with a graphicmarker can be localized in the three-dimensional space with respect toits spatial position as well as with respect to its angular position,and to a great extent independent of location and placement of the imagerecording camera, and without the necessity of the camera calibrationbefore start of the measurements.

Thereby the accuracy of the localization of the graphic marker or theobject to be observed, respectively, is already considerably improvedcompared to the prior art, in that the method according to the inventionnot only allows statements about the position or the deflection,respectively, of the graphic marker compared to the optical axis of theimage recording camera, but also provides the distance between theobject or the graphic marker, respectively, and the image recordingcamera. Based on the thereby always known distance between the objectand the image recording camera, not only just qualitative or approximatestatements can be made, but place and location of the object can bedetermined quantitatively in three-dimensional space with high accuracy.

With the background of the additional determination of movementsequences, it is further provided according to a particularly preferredembodiment of the method according to the invention that for recordingof a location change of the graphic marker or the body part,respectively, the process steps b) to g) are recurring. In this mannersuccessive images of the body part comprising the graphic marker aregenerated, with the successive evaluation thereof by the processordevice, movement sequences or movement curves, respectively, of thegraphic marker or the body part, respectively, can be generated.

According to a further embodiment of the method according to theinvention, in case of at least two relative movable body parts, in eachcase at least one graphic marker is connected with each of the relativemovable body parts. In this manner, the relative position of therespective body parts, respectively the relative positions and relativemovements between the body parts, can be determined and traced with highreliability and accuracy. According to a further embodiment it isprovided, however, that with one and the same body part at least twographic markers are connected. In this manner, the position of the bodypart and also the location of the body part in three-dimensional spacecan be determined with a particularly high accuracy. The latter appliesparticularly in the case when a known geometrical relation, for examplethe known distance between the at least two graphic markers, is alsoconsidered in the evaluation by the processor device.

According to a further embodiment of the method according to theinvention at least two image recording cameras are provided. Here,according to an embodiment, the recording of one and the same graphicmarker takes place by means of at least two image recording cameras. Inthis manner, the reliability and accuracy of the determination of theposition or the location, respectively, of the graphic marker in thethree-dimensional object space can be further increased.

According to a further embodiment, however, with at least one body parttwo graphic markers are connected, wherein each of the graphic markersis associated to different, preferably Cartesian or orthogonal,respectively, space directions, and wherein for each of the spacedirections a separate image recording camera is provided. In thismanner, the determination of the position or angular position,respectively, or the recording of a movement sequence of the body partin three-dimensional space can take place with yet further increasedaccuracy.

As already illustrated at the beginning, the method according to theinvention is suitable for a variety of different application areas inwhich the knowledge about absolute position, relative position or aboutthe movement sequences of body parts is of great interest. According toparticularly preferred embodiments of the method according to theinvention, the determined position data, however, are provided fororthopedic or dental purposes, for example for exact registration of jawmovements. The invention can be used particularly advantageously inthese fields, in particular insofar as the previously used, mostlyelectromechanical methods and recording devices are often associatedwith an extremely high expenditure of equipment, and corresponding highcost, as well as with relative high strain on the patient side.

The invention can further be realized independent of how the usedgraphic marker or the plurality of graphic markers, respectively, isactually formed or which known geometrical characteristics the graphicmarker comprises, respectively, as long as at least a sufficientcontrast exists that allows the capturing and automatic evaluation ofthe recordings from the image recording camera by the processor device.According to a particularly advantageous embodiment of the presentinvention, the graphic marker comprises, however, a majority orplurality of geometrical elements, such as for example, but not in anyway exclusively, lines, blocks, circles or ellipses, wherein each of thegeometrical elements has at least one known and defined geometricalreference with respect to a fixed point of the graphic marker.

Due to the known and defined geometrical reference of the individualcomponents of the graphic marker, for example due to the characteristicdimensions, shapes and/or relative positions of the individualgeometrical elements of the graphic markers to each other, the accuracyof the camera calibration between image space and object space and alsothe accuracy of the detection of the position or location, respectively,of the graphic marker in the object space, can further be increasedconsiderably.

This is associated with the fact that each geometrical element of thegraphic marker, which is additionally recognized by the processordevice, can contribute due to its known dimensions or due to its knownrelative position, respectively, with respect to an also known fixedpoint of the graphic marker, to the accuracy of the localization of thegraphic marker in the image space, and hence also to the improvement ofthe accuracy of the camera calibration. Another advantageous effect ofthis embodiment is that due to the additional geometrical elements andthe thereby given characteristic shape of the graphic marker, a fasterand easier automatic identification and localization of the graphicmarker within the image file provided by the image recording camera ispossible.

It became apparent that with a suitable design of the graphic marker,particularly with a realization of the graphic marker comprising aplurality of geometric elements, for example with a plurality of(additional) line segments, the accuracy of the position determinationof the graphic marker in the image space, and hence the accuracy of thecamera calibration and the position determination of the graphic markerin the object space, can be increased almost as desired. This results inparticular to the crucial advantage that the physical resolution of theimage recording camera does not represent a limiting factor any more forthe accuracy of the position determination of the graphic marker. Infact, by means of a suitable design of the graphic marker or by means ofa suitable arrangement of the geometrical elements of a graphic marker,respectively, an accuracy of the position determination can be achievedwhich reaches far into the sub-pixel range of the image recording cameraor exceeds the physical resolution of the image recording camera by far,respectively.

This means that the method according to the invention, by means of anappropriate formation of the graphic markers suits the most demandingmeasurement tasks as they occur, for example, but by no meansexclusively, in case of the determination of dental ordental-technical-related position and movement data of the jaws. Bymeans of a suitable implementation and design of the graphic markers,relatively inexpensive image recording cameras therefore can be usedwithout the risk that the limited physical resolution of the same wouldrepresent a limitation for the achievable measuring accuracy.

According to a further embodiment of the method according to theinvention, information units are coded based on a characteristicarrangement of the geometrical elements of the graphic marker relativeto each other or relative to a fixed point, respectively, of the graphicmarker. In this manner a multiple advantage of the geometric elements ofthe graphic markers can be achieved as the geometrical elements servefor increasing of the accuracy of the camera calibration and theposition determination of the graphic markers, and also can be used forinformation storage. For example, by means of a suitable characteristicarrangement of some or all geometrical elements of a graphic marker—foran easier automatic association by the processor device—anidentification number of the respective graphic marker can be coded, orcharacteristic dimensions of the respective graphic marker can be storedin this manner.

The method according to the invention can be realized independent of themanner in which the graphic marker is connected with the associated bodypart of the patient. According to an embodiment of the method accordingto the invention it is provided in this context, however, that thegraphic marker is connected with an area of the surface by friction lockor adhesion lock. In this manner, a connection between the graphicmarker and the body part can be realized particularly simple, forexample by forming the graphic marker as a sticker to be placed on theskin or cloth or, for example, by connecting the graphic marker to astocking-like textile structure, which is slipped over the respectivebody part.

With this background, according to a further embodiment of the methodaccording to the invention, it is provided that a correction of thedetermined measuring data is carried out based on collected empiricalvalues for the shifting between the skin surface and the skeleton andwhich empirically arises depending on the relative position of the bodyparts in question. In this manner, the measuring accuracy can beincreased in cases in which the graphic markers for reasons ofsimplicity are glued onto the body surface, and hence are not connectedwith the skeleton.

According to a further preferred embodiment of the method according tothe invention, however, at least one graphic marker is connected with apart of the skeleton. In this manner a particularly high measuringaccuracy can be achieved because the errors caused by shifting of theskin with respect to the skeleton thereby are eliminated. It isparticularly preferable that the graphic marker is connected with atleast one tooth of the upper jaw or the lower jaw, respectively. Hencethe exact position data or movement data, respectively, of the humanskull or head can be determined. Furthermore, in this manner, the dataof the relative position and relative movement of the upper jaw and thelower jaw, which are in particular important for dental anddental-technical purposes, can be determined with the required highaccuracy.

According to a further particularly preferred embodiment of the methodaccording to the invention, the location of the jaw joint axis inthree-dimensional space or the location of the condyles, respectively,hence the joint heads of the lower jaw, is determined automatically bythe processor device from the determined data regarding the position andmovement of the lower jaw or regarding the relative position andrelative movement between the upper jaw and the lower jaw, respectively.This is advantageous insofar as in this manner, the complicated manualdetermination of the location of the jaw joint axis, which in additionis faulty and only allows a location determination with medium accuracy,is eliminated and replaced by the automatic location determination ofthe jaw joint axis. The knowledge about the location of the jaw jointaxis is of great importance in many areas of dental diagnosis, sincediverse data relevant for diagnostic and dental purposes with respect tothe jaw movement and the occlusion often use the jaw joint axis and thecondyles of the lower jaw as a reference.

With this background it is particularly preferably provided that thedetermined position or movement data of the lower jaw, respectively therelative position or relative movement data between upper jaw and lowerjaw, by means of a coordinate transformation by the processor device,are automatically referenced to a point located on the jaw joint axis.In this manner a uniformity of the obtained data and an associatedstandardized data usability are ensured. Additionally, the comparison ofthe data obtained in this manner about the movement sequence of thelower jaw, with similar data, which, however, were generated, forexample, in a conventional way with a mechanical or electronicpantograph known from the prior art, is made easier in this manner. Afurther advantage of this embodiment is that the graphic markers, due tothe automatic transformation of the measuring data onto a point locatedon the jaw joint axis, can to a large extent be placed freely and atwill. The need to place the graphic marker exactly at predeterminedpoints of the jaw is eliminated in this manner, which essentiallyaccommodates the uncomplicated measuring sequence and the quickobtaining of the desired measured values.

According to a further preferred embodiment of the method according tothe invention, from the determined position data or movement data,respectively, of the lower jaw, by means of the processor device,relevant diagnostic or dental-technical data such as condyle axisposition and shifting, condyle path inclination and behavior, Bennettangle, side shift and the like, are derived automatically; from thedetermined relative position or relative movement date of the jaw and bymeans of known or measured skull data, the location of any point of thelower jaw is determined; or from the determined position and movementdata, parameters for adjustment of dental-technical articulators arederived.

Such automated processing of measuring data obtained on the jaw is ofgreat advantage and of crucial importance for the reliable dental ororthodontic analysis and diagnosis, respectively, as well as for costeffective, quick and accurate performance of dental-technical work bythe dental technician, as, for example, for the fabrication of dentalprosthesis by means of articulators.

The invention can be realized independent of the manner in which thegraphic marker is connected with the body part or one of the jaws of thepatient, respectively, as long as a simple, reliable and as accurate aspossible reproduction of the position or movement, respectively, of therespective body part, is given by the graphic marker. According to aparticularly preferable embodiment of the method according to theinvention for this, however, a bite plate is arranged by means of aplastic bite compound on the dental arch of the lower jaw. Thereby, thebite plate is connected with the at least one graphic marker. In thismanner a simple and easily detachable connection between the dentalarch, respectively the lower jaw, and the graphic marker arises, whichin addition, due to the freedom of play, allows a highest possibleaccuracy for the position measurement and movement tracing.

The invention relates further to a device for recording of position,location or movement of at least a part of the body of a patient or amedical instrument. In an initially known manner, taken by itself, thedevice comprises at least a graphic marker connectable with the objectcomponent—hence with the at least one body part of the patient or withthe at least one part of the medical instrument—and at least one imagerecording camera, wherein the image recording camera is arranged andequipped in a manner that with the image recording camera at least oneimage of the object component comprising the graphic marker can begenerated. The recording device comprises further a processor device forautomated processing of image information which is contained in theimage generated by the image recording camera.

For this purpose, the device can be formed for position or movementtracing of either the body part of the patient or the medicalinstrument, or for position or movement tracing of the body part of thepatient as well as of the medical instrument. In particular, in thelatter case thereby statements can be made about the relative positionor relative movement, respectively, between the body part of the patientand the medical instrument, which are especially of importance duringmanual or automated surgical interventions.

According to the invention, the recording device distinguishes itself inthat at least one geometrical size characteristic of the graphic markeris known and receivable in a storage of the processor device. For thispurpose, the processor device is equipped for determination of position,angular position and/or the movement path of the graphic marker relativeto the image recording camera by means of the known size characteristicand by means of the dimensions thereof in the image space.

In other words, this means with that the device according to theinvention distinguishes itself by an automatic camera calibration,wherein the camera calibration takes place automatically by means ofknown information about the dimensions of the graphic marker.

Compared to the prior art, thanks to the device according to theinvention, the localization or the movement tracing, respectively, ofthe object components, therefore of the parts of a body or of a medicalinstrument, respectively,—in particular due to the automatic cameracalibration—can hence basically be considerably simplified. Furthermore,the device according to the invention allows the determination of theposition in three-dimensional space as well as, if necessary, thedetection of the angular position of the object component or the graphicmarker, respectively, connected with the object component relative tothe image recording camera. Thanks to the device according to theinvention, for example, a body part of a patient provided with a graphicmarker or a medical instrument can hence be localized inthree-dimensional space with regard to its spatial position as well aswith regard to its angular position.

The accuracy of the localization is in particular considerably improvedalready compared to the prior art in that the method according to theinvention not only allows statements about the position of the graphicmarker compared to the optical axis of the image recording camera, butalso provides the distance between object or graphic marker,respectively, and image recording camera.

According to a preferred embodiment, the recording device according tothe invention distinguishes itself in that at least two graphic markersare provided, wherein for the case of at least two relative movable bodyparts or object components, respectively, in each case at least onegraphic marker is associated to each of the relative movable objectcomponents. In this manner also the relative position of the objectcomponents, respectively the relative movements between the objectcomponents, for example, between two different body parts or between twodifferent limbs of an extremity, can be determined with high reliabilityand accuracy.

A further embodiment provides that to one and the same object componentat least two graphic markers are associated. Therefore, with therecording device, the position of the object component as well as thelocation of the object component in three-dimensional space can bedetermined with particularly high accuracy. This applies in particularthen, when the processor device is equipped in a manner that the knowngeometrical relation—for example, the known distance between the twographic markers—can also be included in the evaluation by the processordevice.

According to a further embodiment of the recording device, at least twoimage recording cameras are provided. Here the image recording camerasaccording to an embodiment are equipped in a manner that one and thesame graphic marker can be recorded by the at least two image recordingcameras. In this manner the reliability and accuracy of the positiondetermination or location determination, respectively, in thethree-dimensional object space is further increased.

According to a further embodiment of the recording device according tothe invention, to at least one object component, however, at least twographic markers are associated, wherein the graphic markers are providedfor arrangement in different, preferably Cartesian or orthogonal spacedirections, respectively, and wherein for each of the space directions aseparate image recording camera is provided.

In this manner, the accuracy of the determination of the position orangular position, respectively, or the accuracy of the recording of amovement sequence of the object component in three-dimensional space canbe further increased.

The invention is realized independent of how the at least one usedgraphic marker is concretely formed or which geometrical features thegraphic marker comprises, respectively, as long as a sufficient contrastexists, which allows the capturing and automatic evaluation of therecordings from the image recording camera by the processor device.According to a particularly preferred embodiment of the invention, thegraphic marker comprises, however, a majority or plurality ofgeometrical elements such as, for example, blocks, circles or ellipses,wherein each of the geometrical elements comprises at least one knownand in each case defined geometrical reference with respect to a fixedpoint of the graphic marker.

Due to the known and defined geometrical reference of the individualcomponents of the graphic marker—for example due to the characteristicdimensions, shapes and/or relative positions of the individualgeometrical elements of the graphic markers to each other—the accuracyof the camera calibration between image space and object space and alsothe accuracy of the detection of the position or location, respectively,of the graphic marker in the object space, can further be increasedconsiderably. A further advantageous characteristic of this embodimentis that due to the additional geometrical elements, a faster and easierautomatic identification and localization of the graphic marker in theimage file provided by the image recording camera can take place, sincea graphic marker formed in such a manner stands out clearly and with alower likelihood of confusion against the background, respectivelyagainst other image elements contained in the image file.

This means that the device according to the invention, by means ofappropriate formation of the graphic marker, can be used for demandingmeasuring tasks with the highest requirements in accuracy, as thisis—for example—the case in the orthodontic diagnosis or during thedetermination of relevant dental or dental-technical position andmovement data of the jaws, respectively. By means of a suitableimplementation and design of the graphic markers, relative inexpensiveimage recording cameras therefore can be used without the risk that thelimited physical resolution of the same would represent a limitation forthe achievable measuring accuracy.

According to a further embodiment of the device according to theinvention, information units are coded based on a characteristicarrangement of the geometrical elements of the graphic marker relativeto each other or relative to a fixed point of the graphic marker,respectively. In this manner, a multiple advantage of the geometricalelements of the graphic markers can be achieved as the geometricalelements serve for increasing of accuracy of the camera calibration andthe position determination of the graphic markers, and also can be usedfor information storage. For example, by means of a suitablecharacteristic arrangement of some or all geometrical elements of agraphic marker—for an easier automatic identification by the processordevice—a separate identification number for each graphic marker can becoded, or characteristic dimensions of the respective graphic marker, inthe pattern of the graphic marker itself, can be stored in this manner.

The invention can be realized independent of the manner in which thegraphic marker is connected with the associated object component,therefore with the associated body part of the patient, or with theassociated part of the medical instrument. According to an embodiment ofthe invention, the device is equipped for a friction lock or adhesionlock connection of the graphic marker with an area of the objectsurface. In this manner, a connection between the graphic marker and theobject component can be realized particularly simple and quick, forexample by forming the graphic marker as a sticker to be placed on theskin, cloth or instrument, or, for example, by connecting the graphicmarker to a stocking-like textile structure, which is slipped over therespective body part.

According to a further preferred embodiment of the recording deviceaccording to the invention, the device is equipped for connection of thegraphic marker with a part of the skeleton. In this manner aparticularly high measuring accuracy can be achieved, in particularbecause the errors caused by shifting of the skin with respect to theskeleton thereby are eliminated. With this background, the devicecomprises, according to a further embodiment, a mounting arrangement forconnecting the graphic marker with at least one tooth of the upper jawor the lower jaw. In this manner, exact position data or movement data,respectively, of the human skull or head can be determined. Furthermore,in this manner, the data of the relative position and relative movementof the upper jaw and the lower jaw, which are in particular importantfor dental and dental-technical purposes, can be determined with therequired high accuracy.

The device according to the invention can be used regardless of adefined relation or mechanical fixation between the device and the bodyof the patient or the medical instrument, respectively, exists or not.Thus it is in particular possible to determine and trace relativemovements between the different object components with high accuracy,without any defined mechanical connection between the recording deviceand the traced object or patient, respectively, being present.

According to a preferred embodiment of the invention, the recordingdevice comprises, however, a mechanism for fixation of the at least oneimage recording camera relative to a part of the body or skeleton,respectively, of the patient. In particular for the case of usage of therecording device according to the invention in the field of the dentalanalysis and diagnosis, such a fixation between the image recordingcamera and the patient can be carried out, for example, in the form of abelt, a specific head rest or an elastic clamp, wherein belt, head restor clamp are applied on the skull, respectively head, of the patient.

In this manner, the head or the skull bone of the patient, respectively,and therefore also the upper jaw, is brought in a defined andtemporarily fixed relative position to the recording device or imagerecording camera, respectively, connected with the belt, head rest orclamp. This serves on the one hand for simplification of the performanceof the measuring process and on the other hand for the further increaseof the measuring accuracy. In addition, the application of graphicmarkers on the upper jaw or in the area of the skull or head of thepatient, respectively, can hence be abandoned.

According to a further preferred embodiment, the recording device isconnectable with a display unit. For this purpose, the processor unit ordisplay unit, respectively, are equipped in such a manner that by meansof the determined position, location and/or movement path of the atleast one graphic marker, diagnostically relevant data and relations,such as condyle axis position and shifting, condyle path inclination andcourse, Benett angle, side shift or Posselt schema, can be automaticallydetermined or displayed graphically or numerically, respectively.

The automatic processing and display of the measuring data obtained onthe jaw is crucial during the dental or orthodontic analysis anddiagnosis, respectively, as well as during the performance ofdental-technical work—as, for example, during the fabrication of dentalprosthesis by means of an articulator—by the dental technician.

With this background it is further provided according to anotherembodiment of the invention that the recording device is equipped forautomatic determination of characteristic parameters for the immediateadjustment of different types of dental-technical articulators. In thismanner, the relevant orthodontic or dental data, respectively,determined with the recording device according to the invention can betransferred reliably with minor expenditure to each articulator used bythe dental technician.

Hereafter the invention is described in detail by means of a drawingillustrating only an exemplary embodiment.

In the only FIGURE shows

FIGURE a not-to-scale schematic illustration of an embodiment of adevice according to the invention in an isometric view.

In the FIGURE an embodiment of a recording device according to thepresent invention is illustrated in a highly schematic manner. Therecording device illustrated in the FIGURE is provided for useparticularly in the dental practice and serves for the so-called lowerjaw registration or for the associated recording of the movement pathsof the lower jaw, respectively, when opening the mouth, during occlusionmovements and the like.

To begin with, the head 1 of the patient can be seen, which is fixed bymeans of an elastic, cushioned clamp 2 relative to a base 3 of therecording device. Instead of the cushioned clamp 2, for example, aspecific head rest can also be used, wherein in this case the recordingdevice is preferably connected with the head rest or the head portion,respectively, of a treatment chair of the dental practice.

At the base 3 of the recording device, besides the cushioned clamp 2 forfixation of the head 1 of the patient, an adjustable camera bracket 4 isarranged. At the camera bracket 4 of the illustrated embodiment, threehighly schematically sketched image recording cameras 5, 6, 7 arearranged, the lenses 8 of which at first are pointing approximatelytowards the patient. Preferably conventional and inexpensive CCD cameraswith, for example, USB or Firewire interface can be used here. The imagerecording cameras 5, 6, 7 are variably attached to the camera bracket 4so that the most spacious adjustability of the image recording camera 5,6, 7 relative to the base 3 of the recording device, respectivelyrelative to the patient's head 1, is given.

The patient carries a bite plate (not shown in the FIGURE) in the mouth,which is connected with the teeth of the lower jaw by means of a plasticbite compound and hence follows all movements of the lower jaw. With thebite plate a number of marker areas 9 is connected. With respect to themouth of the patient in anterior position, the marker areas 9 arearranged on a square rod 10, wherein the square rod 10 in turn isconnected with the bite plate arranged in the mouth of the patient.Laterally with regard to the head 1 of the patient in the approximateregion of the jaw joints, further marker areas 9 are located, which inthe illustrated embodiment are formed in the form of the surfaces ofangle profiles 11. Here the angle profiles 11 comprising the lateralmarker areas and the square rod 10 carrying the anterior marker areasare coupled by means of a light connection bow 12, which is easilyremovable from square rod 10.

On each of the marker areas 9, in the anterior 10 as well as in thelateral region 11, a number of graphic markers or markers 13,respectively, are arranged. For reasons of simplicity andpresentability, the markers 13 in the illustrated exemplary embodimentare illustrated as simple black circles.

Apart from the cushioned clamp 2 or a corresponding head rest,respectively, and the bite plate including the marker areas 9 connectedthereto, unlike the prior art, no further devices, measuring brackets,sensor holders or the like to be connected with the head 1 of thepatient are required. This results in fundamental advantages withrespect to the performance of the registration of the lower jaw executedaccording to the invention, which is fast and uncomplicated for the userand hardly stressful for the patient.

For measuring the movement paths of the lower jaw of the patient, theimage recording cameras 5, 6, 7 are oriented by means of a correspondingdisplacement of the camera bracket 4 or by means of a displacement ofthe individual cameras 5, 6, 7, respectively, relative to the camerabracket 4 such that the visual field of each camera 5, 6, 7 captures anumber of graphic markers or markers 13, respectively. In this state,the image files or pixel images, respectively, generated by the imagerecording cameras 5, 6, 7 are evaluated in regular time intervals by theprocessor device 14 according to the invention.

In the illustrated embodiment, the measurement can either take placeclose to the jaw joint by recording and tracing of the lateral markerareas and graphic markers arranged on the angle profiles 11, or ameasurement can take place by means of the frontal pin or square rod 10,respectively, by pointing the image recording cameras 5, 6, 7 towardsthe marker areas arranged anterior on the square rod 10. For themeasurement with the frontal pin, therefore, the connection bow 12 withthe marker areas and graphic markers arranged close and lateral at 11 tothe jaw joint is not needed and can hence be removed together with theangle profiles 11, which, concerning the equipment, results in anextremely simple measuring system including only a bite plate and squarerod 10, which is virtually stress-free for the patient.

The measurement takes place each time in such a manner that theprocessor device 14, by means of an image recognition algorithm, checksthe image files or pixel images, respectively, provided by the imagerecording cameras 5, 6, 7 for the images of the graphic markers ormarkers 13, respectively, contained in each of the pixel images andsubsequently automatically determines, by means of the method accordingto the invention, the position of the graphic markers or markers 13,respectively, found in the pixel images in three-dimensional space.

Since, according to the invention, the absolute position of the graphicmarkers in three-dimensional space relative to each of the associatedcameras 5, 6, 7 can be determined and since, furthermore, the methodaccording to the invention and the device according to the inventionallow an accuracy of the position tracing of the graphic markers whichreaches far into the sub-pixel range of the image recording cameras 5,6, 7, the illustrated device allows the registration or recording,respectively, of the movements of the lower jaw with an accuracyvirtually previously not achieved by the prior art.

This is firstly associated in particular with the fact that according tothe invention an automatic calibration of the image recording camera 5,6, 7 takes place, whereby the processor device 14, by means of thedimensions of the graphic markers or marker 13, respectively, determineson the pixel image provided by the respective camera 5, 6, 7 and bymeans of the known geometry data or by means of the real dimension dataof the graphic markers in the object space, respectively, the actualdistance between the respective graphic marker and the associated imagerecording camera 5, 6, 7. Furthermore, this automatic calibration of theimage recording cameras 5, 6, 7 by the processor device 14 can becontinuously renewed—for example even within the processing of eachindividual single image—so that at each point in time the exact distancebetween image recording camera 5, 6, 7 and the graphic marker or marker13, respectively, is known.

By means of the hereby determined known distance between the graphicmarker or marker 13, respectively, and the associated image recordingcamera 5, 6, 7, however, the absolute position of the graphic markerrelative to the image recording camera 5, 6, 7 can be determined inconsideration of the imaging properties of the camera lens. This is oneof the crucial differences compared to the prior art, where eitherabsolute measurements are completely abandoned, whereby primarilyqualitative statements about the recorded movement paths are possible,or where a complicated manual calibration of the used cameras or sensorsystems is required.

Another crucial factor of the extremely high accuracy of thelocalization and the tracing of the graphic markers or markers 13,respectively, achieved with the illustrated recording device is that bymeans of suitable formation of the graphic markers, the accuracy of theposition tracing can be increased almost as desired. For this, in theillustrated embodiment, besides the known diameter of the individualmarkers 13, for example, the known distance between respectively twomarkers 13 arranged on the same marker area 9 is also used. Already,with the additional utilization of the known distance between themarkers 9 arranged in pairs, the accuracy of the camera calibration canbe increased and the precision of the localization and the tracing ofthe graphic markers can be improved by further orders right into themicrometer range.

This is in particular associated with the fact that each knowngeometrical feature and each known dimension of the graphic markerincreases the accuracy of the localization and the tracing of thegraphic marker within the image file provided by the image recordingcamera 5, 6, 7. By each additional geometrical feature of the graphicmarker, the information content of the image of the graphic marker,which is evaluable by means of appropriate image recognition algorithms(for example Hough transformation), is increased; and additionally ineach case an accordingly increased number of image information, forexample, image pixels is available, which hence can be used for an evenmore accurate localization of the graphic marker.

For recording of the complete movement sequence of the lower jaw, in theillustrated exemplary embodiment, the marker areas 9 with a graphicmarker arranged thereon, which are arranged in the anterior mouth regionon the rod 10, and, in principal, only a single one of the threepresently used image recording cameras 5, 6, 7 would be alreadysufficient. The additional marker areas, which are arrangeable in thelateral head area in the region of the jaw joints 11, or the graphicmarkers, respectively, and the presently used number of three imagerecording cameras 5, 6, 7, hence serve mainly for the increase of theaccuracy during the movement tracing of the lower jaw. Thereby, theimage recording camera 7 arranged in the upper area of the camerabracket serves mainly for the accurate recording of the lateralmovements, hence the side shift behavior of the lower jaw, whichnormally occurs with mouth opening movements.

Furthermore, the connection bracket 15 visible in the front region ofthe recording device serves for the simple adjustment of the rotationposition of the two lateral cameras 5 and 6, wherein the connectionbracket can be removed after completed adjustment of the cameras 5 and 6to allow free access to the patient 1. The adjustment of the rotationposition of the lateral cameras 5 and 6 serves for setting the obtainedmeasuring data or movement curves, respectively, of the lower jaw inrelation to the actual position of the skull or head 1 of the patient,respectively.

Thereby the camera adjustment of the lateral cameras 5 and 6 takes placein a manner that the lateral-arranged image recording cameras 5 and 6are pivoted or rotated, respectively, by means of the connection bracket15 around the camera axis until the connection bracket 15 and hence arespectively defined horizontal axis of the camera 5, 6 is oriented inparallel to the Frankfurt horizontal, thus to the virtual connectionline between the porion (the upper margin of the external auditorymeatus) and the orbital cavity (osseous eye socket).

Apart from the processor device 14, the illustrated recording device orregistration device, respectively, comprises further, or is connectedwith, respectively, an output device 16, for example a monitor and or aprinter, a control panel 17, for example, a keyboard, an (external)storage device 18, for example a USB memory stick, and a data connectionto an external computer 19, for example a personal computer, inparticular to be able to carry out further detail evaluation of thedetermined measuring data thereon.

As a result it hence appears that by means of the invention thepossibilities for recording or tracing, respectively, of position,location or movement of parts of the body of a patient or a medicalinstrument, respectively, can be drastically broadened and at the sametime also simplified. The invention thereby allows a high degree ofautomation as well as a high measuring accuracy during the positiondetermination and the movement tracing, wherein at the same time theequipment expenditure is dramatically reduced and the reaction to theobject or the body part to be measured or the patient, respectively, isminimized.

The invention hence provides a crucial contribution for improvement ofabsolute and relative positions or movements, respectively, particularlyin fields, such as for example, in the manual or automated surgery or inthe dental jaw registration, where highest measuring accuracy and asimple applicability represent central application criteria.

The invention claimed is:
 1. A method for recording of three-dimensionalposition, location or movement of at least one part of a body of apatient arranged in an object space by means of electronic imagerecognition using at least one image recording camera, whereby position,location or movement is recorded three-dimensionally independently byeach one image recording camera, the method comprising the followingprocess steps: a) Connecting at least one movable graphic marker with atleast one body part, wherein at least one geometrical sizecharacteristic of the graphic marker is known; b) Generating an image ofat least the area of the body part containing the graphic marker witheach image recording camera; c) Transferring the image of each imagerecording camera as an image file into an electronic processor device;d) In the image space of each image file, localizing of the image of thegraphic marker contained in the image file by means of application of anautomated image recognition procedure to the image file; e) Determiningthe size characteristic of the graphic marker in each image space; f)Calibrating the recording system by determining three-dimensionalabsolute position data of the graphic marker in the object spacedirectly relative to each one image recording camera by means ofcalculating distance and angle between the graphic marker and therespective image recording camera using the size characteristic of thegraphic marker in the image space as determined by the respective imagerecording camera and the known size characteristic of the graphic markerin the object space together with the imaging properties of therespective camera lens; g) Transferring the determined data regardingthe three-dimensional absolute position of the graphic marker in theobject space into a data storage wherein at least steps b) to f) arecarried out independently for each camera and its respective image. 2.The method according to claim 1, characterized in that for recording ofa location change of the graphic marker or a movement sequence of thebody part, respectively, the process steps b) to g) are repeated.
 3. Themethod according to claim 1, wherein at least one graphic marker isconnected with each of at least two relative moveable body parts.
 4. Themethod according to claim 1, characterized in that with the at least onebody part at least two graphic markers are connected.
 5. The methodaccording to claim 1, characterized in that at least two image recordingcameras for recording of images of the at least one graphic marker areprovided.
 6. The method according to claim 5, characterized in that withat least one body part at least two graphic markers associated todifferent space directions are connected, wherein for each of the spacedirections a separate image recording camera is provided.
 7. The methodaccording to claim 6, characterized in that the different spacedirections correspond to an Cartesian coordinate system.
 8. The methodaccording to claim 1, characterized in that the determined position dataare used for orthopedic or dental purposes or for registration of lowerjaw movements, respectively.
 9. The method according to claim 1,characterized in that the graphic marker comprises a majority orplurality of geometrical elements, wherein each of the geometricalelements has at least one known, defined geometrical reference to afixed point of the graphic marker.
 10. The method according to claim 9,characterized in that by means of a characteristic arrangement of thegeometrical elements relative to each other and/or relative to a fixedpoint of the graphic marker, information units are coded.
 11. The methodaccording to claim 1, characterized in that the graphic marker isconnected with an area of the surface of the body part by friction lockor adhesion lock.
 12. The method according to claim 11, wherein at leastone graphic marker is connected with each of at least two relativemovable body parts, and depending on the determined relative position ofthe at least two body parts, a correction of the determined measuringdata takes place by means of empirical values for the shifting betweenthe skin surface and the skeleton occurring in dependency of therelative position of the body parts.
 13. The method according to claim1, characterized in that the graphic marker is connected with a part ofthe skeleton.
 14. The method according to claim 1, characterized in thatthe graphic marker is connected with at least one tooth of the upper orlower jaw.
 15. The method according to claim 14, characterized in thatby means of the processor device, the location of the jaw joint axis orthe condyles, respectively, is determined automatically from thedetermined position or movement data of the lower jaw.
 16. The methodaccording to claim 15, characterized in that the determined position ormovement data of the lower jaw are related by means of a coordinatetransformation to a point located on the jaw joint axis.
 17. The methodaccording to claim 14, characterized in that by means of the processordevice, relevant dental or dental-technical data, respectively, such ascondyle axis position and shifting, condyle path inclination andbehavior, Bennett angle, side shift and the like, are derivedautomatically from the determined position or movement data.
 18. Themethod according to claim 14, characterized in that by means of theprocessor device, from the determined position and movement data as wellas by means of skull data, the location of any point of the lower jaw isdetermined.
 19. The method according to claim 14, characterized in thatby means of the processor device, from the determined position ormovement data, parameters for adjustment of dental-technicalarticulators are derived.
 20. The method according to claim 14,characterized in that a bite plate is arranged on the dental arch of thelower jaw by means of a bite compound, wherein the bite plate isconnected with at least one graphic marker.
 21. A device for recordingof position, location or movement of at least a component of the body ofa patient or a medical instrument, the device comprising at least onemovable graphic marker connectable with the object component and atleast one image recording cameras, wherein each image recording camerais equipped for generation of at least one image of the object componentcomprising the graphic marker, the device further comprising a processordevice for automated processing of image information contained in theimage, characterized in that at least one geometrical sizecharacteristic of the graphic marker is known and transferable in astorage of the processor device, wherein the processor device isequipped for determination of position, location and/or movement path ofthe graphic marker three-dimensionally directly relative to each imagerecording camera independently for the image(s) of each image recordingcamera by means of the known size characteristic as well as by means ofits dimensions in the image space.
 22. The device according to claim 21,characterized by at least two graphic markers, wherein each of thegraphic markers is associated to respectively one of the at least tworelative-movable object components.
 23. The device according to claim21, characterized by at least two graphic markers, wherein the at leasttwo graphic markers are associated to the same object component.
 24. Thedevice according to claim 21, characterized by at least two imagerecording cameras for recording of images of the at least one graphicmarker.
 25. The device according to claim 21, characterized in that toat least one object component at least two graphic markers arranged indifferent space directions are associated, wherein the device comprisesa separate image recording camera for each space direction.
 26. Thedevice according to claim 25, characterized in that the different spaceorientation corresponds to a Cartesian coordinate system.
 27. The deviceaccording to claim 21, characterized in that the graphic markercomprises a majority or plurality of geometrical elements, wherein eachof the geometrical elements in the object space has at least one known,defined geometrical reference to a fixed point of the graphic marker.28. The device according to claim 27, characterized in that by means ofa characteristic arrangement of the geometrical elements relative toeach other and/or to a fixed point of the graphic marker, informationunits are coded.
 29. The device according to claim 21, characterized inthat the device is equipped for a friction lock or adhesion lockconnection of the graphic marker with an area of the body surface. 30.The device according to claim 21, characterized in that the device isequipped for a connection of the graphic marker with a part of theskeleton.
 31. The device according to claim 21, characterized in thatthe device comprises a mounting arrangement for connection of thegraphic marker with at least one tooth of the upper or lower jaw. 32.The device according to claim 21 characterized in that the devicecomprises a mechanism for fixation of the image recording camerarelative to a part of the body or skeleton, respectively.
 33. The deviceaccording to claim 31, characterized in that the processor device isconnectable with a display unit, wherein the processor device or thedisplay unit, respectively, is equipped by means of the determinedposition, location and/or movement path of the at least one graphicmarker for automatic determination or for graphical or numericaldisplay, respectively, of dental-relevant relations, such as condyleaxis position and shifting, condyle path inclination and behavior,Bennett angle, side shift, Posselt schema and the like.
 34. The deviceaccording to claim 31, characterized in that the device is equipped forautomatic determination of parameters for adjustment of dental-technicalarticulators.